The centerpiece of this training grant is translational research that takes findings from basic cognitive science, including the applicant's previous research, and applies them to understanding why bipolar spectrum disorders are often misdiagnosed in clinical practice. The latter is common: up to 40% of people with bipolar disorder will be originally misdiagnosed; under-diagnosis of less severe bipolar disorders may be even more common. The aim of the grant is to improve diagnosis by exploring how memory processes affect patients' ability to report past symptoms of bipolar disorder. The proposal also entails a significant training component designed to prepare the applicant for a research career focused on elucidating the phenomenology of bipolar spectrum disorders, as well as improving their assessment and treatment. The reason for the high rate of bipolar misdiagnosis remains speculative. One possibility is that mood state dependent memory biases associated with depression interfere with the recall of past symptoms of hypomania/mania. Cognitive studies show that depression produces mood-congruent memory biases. The latter refers to the tendency of people with depression to recall information that is congruent with their mood-state. Typically, studies of these biases have been limited to showing biases for general autobiographical memories or word lists. No study has tested whether depressive memory biases generalize to a patient's ability to recall past symptoms of hypomania/mania. If they do, then a significant portion of "unipolar" depression patients may turn out to have bipolar disorder when reassessed after their depression remits. To test this hypothesis, the proposed study will follow-up with a group of patients (n = 122) who receive a diagnosis of unipolar major depression and deny past hypomania/mania. The severity of memory biases, as well as overall memory functioning, will be assessed. Six months after their initial evaluation, participants will be reassessed for bipolar disorder. We expect a significant number of "unipolar" patients will be re- diagnosed as having bipolar disorder at follow-up if their depression symptoms have remitted. We also expect changes in the number of past hypomania/mania symptoms reported between assessments to be correlated with changes in mood-congruent memory biases. To control for confounds, a non-depressed, non-bipolar control group (n = 122) will also be reassessed after six months (total N = 244). Relevance: Findings will help clinicians detect bipolar disorders, which has major public health benefits. Under recognition of bipolar disorders is associated with a worse course of symptoms for patients (more frequent mood disorder episodes) and with much greater treatment costs for the healthcare system. [unreadable] [unreadable] [unreadable]